The new Pro tier for BitTorrent Sync costs $40/year, which falls roughly in line with other services like Dropbox or Google Drive (depending on your storage needs, of course, though Sync has no limits). With the Pro version you can make all your files accessible on any device, while only selectively syncing them. You also get improved access controls for sharing files.

Free users can still use the service for up to 10 folders. Because Sync uses peer-to-peer technology for its transfers, there's no limit to the size or speed of the files you're allowed to sync. You can also install Sync on NAS systems so you can access your own personal server from anywhere.